In recent years, efforts have been actively made to apply a device which mixes fluids in a fine flow path prepared by a micro processing technique or the like, namely a microreactor, to biotechnology field, medical field, and chemical synthesis field of medicines, chemical products, or the like.
Synthesis reactions in a microreactor have the following features. That is, as the size of the reaction field in the microreactor decreases, fluids are mixed rapidly due to molecular diffusion. As a result, the effect of surface area on the volume of the fluid becomes relatively large, and the effect of heat transfer on the volume of the fluid becomes relatively large. Therefore, compared to general batch reactions, the production efficiency is expected to be improved by shortened reaction time and yield improvement.
Since the microreactor is a closed system which provides a small reaction field, the microreactor is suitable for handling highly corrosive substances and dangerous synthesis reactions. Even if the productivity of a single microreactor is small, the same product can be produced in large quantities by multiplying the number of the microreactors by N times, that is, so-called “numbering-up”.
In addition, in the field of biotechnology or medicine synthesis, although the corrosiveness of the substance to be handled is relatively low, cross-contamination caused by inclusion of foreign matters from the outside is usually not preferred.
By using resins such as PDMS (polydimethylsiloxane), ABS resin, or PC (polycarbonate) as the material, the cost of material and molding process is reduced, so that the microreactor is for single use (disposable).
Various developments and studies have been carried out with respect to a flow path structure of a microreactor which is oriented for application to each of the fields mentioned above and in which two types of fluids are rapidly mixed.
As a first method, there has been known a technique in which two types of raw materials are each branched into a plurality of parts, and can be alternately introduced in a radial manner to form multilayer flows toward the center and merge with one another (refer to, for example, PTL 1 and PTL 2).
PTL 1 (refer to claim 1) describes a micro-device which “supplies two or more incoming fluids independently to a merging area and discharges the fluids from the merging area, comprising: supplying channels configured to supply each incoming fluid of the micro-device respectively to the merging area; and a discharging channel configured to discharge the merged fluids from the merging area to the outside of the micro-device, wherein the supplying channel, which supplies at least one fluid, has a plurality of sub-channels merging in the same merging area, the sub-channels and the supplying channels are configured such that a central axis of at least one of the plurality of sub-channels and a central axis of at least one of the supplying channels or the sub-channels supplying at least one of the fluids other than the fluid supplied by the above sub-channel intersect with each other at a point” and a method for merging of fluids.
In addition, PTL 2 (refer to claim 1) describes a method for producing organic pigment fine particles, comprising “allowing two or more solutions, at least one of which is an organic pigment solution in which an organic pigment is dissolved and at least one of which is a pH adjustor, to flow through a micro flow path in a non-laminar state; and depositing organic pigment fine particles from the organic pigment solution in a process of flowing, wherein the organic pigment solution is a solution in which an organic pigment is dissolved in an alkaline or acidic aqueous medium, the organic pigment fine particles are deposited by changing a hydrogen ion exponent (pH) of the organic pigment solution in the process of flowing in the micro flow path, and intersection angles α and β upon merging of solutions of the organic pigment solution and the pH adjustor are set to satisfy a relationship of S1>S2 if a sum of the cross-sectional areas of all of the merged solutions in the thickness direction is defined as S1 and the cross-sectional area of the micro flow path in the radial direction is defined as S2”.
In addition, as a second method, there has been known a technique in which two types of raw materials are each branched into a plurality of parts, and one type of the branched raw materials merges in a way of being sandwiched by the other type of branched raw materials, so as to finally perform the merging (for example, refer to PTL 3).
PTL 3 describes an emulsifying device “comprising an introducing member; a first member connected with the introducing member; a second member connected with the first member; a third member connected with the second member; and a discharge member connected with the third member, in a laminated manner. In each of a dispersion phase inflow path through which a first liquid flows and which penetrates the introducing member and the first member in a lamination direction; a continuous phase inflow path through which a second liquid which is dissoluble in the first liquid flows, and which is provided between the first member and the second member; a mixing flow path which penetrates the second member in the lamination direction and configured to form a sheath flow in which the first liquid flowing from the dispersion phase inflow path flows on an inner side, the second liquid flowing from the continuous phase inflow path flows on an outer side to form a mixed liquid; and an enlarged mixing flow path which penetrates the third member and the discharge member in the lamination direction and has a larger flow path width than the mixing flow path, the dispersion phase inflow path, the mixing flow path, and the enlarged mixing flow path are provided coaxially, the mixing flow path and the enlarged mixing flow path are formed on separate members respectively, the first liquid contained in the mixed liquid is divided while flowing in the mixing flow path and the enlarged mixing flow path so as to form emulsion particles, and thus emulsification is performed”.